The arc-melting of niobium, tantalum, molybdenum and tungsten

Moss, A.R.; Richards, D.T.

doi:10.1016/0022-5088(60)90024-2

Cited by 12 publications

(5 citation statements)

References 16 publications

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“…Various chemical processes like alumino-thermic, magnesio-thermic, calcio-thermic and sodium reduction employed to prepare highpure tantalum have not reduced metallic impurities below a few tens of ppm [9][10][11][12]. High purity tantalum is usually prepared by electron beam melting (EBM) and vacuum arc remelting (VAR) [13] and Ar/Ar-H 2 plasma arc melting [14]. Tantalum purification by EBM is more efficient when compared to VAR due to the fact that the high vacuum helps in better vaporization of metalic impurities as well as interstitial gases.…”

Section: Introductionmentioning

confidence: 99%

Preparation of 5N grade tantalum by electron beam melting

Choi

Lim

Munirathnam

et al. 2009

Journal of Alloys and Compounds

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Section: Introductionmentioning

confidence: 99%

Preparation of 5N grade tantalum by electron beam melting

Choi

Lim

Munirathnam

et al. 2009

Journal of Alloys and Compounds

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“…The manufacturing route through which tungsten components are manufactured also impacts the weldability. Parts produced via arc-casting (A-C) claimed greater fabricability and higher purity, when compared to components manufactured via powder metallurgy (PM) or chemical vapour deposition (CVD) routes [9,11,12]. In fact, when joining tungsten components manufactured via PM and CVD, porosity usually develops [10].…”

Section: Introductionmentioning

confidence: 99%

Effect of shielding gas composition and welding speed on autogenous welds of unalloyed tungsten plates

Marinelli

Martina

Ganguly

et al. 2019

International Journal of Refractory Metals and Hard Materials

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Tungsten usually exhibits poor weldability and marked brittleness at room temperature. This cause tungsten welds to be affected by the evolution of cracks along the weld bead, which can be eliminated by using a pre-heating step to reduce thermal straining. In this study, based on the tungsten inert gas welding process, a working envelope, focussed on varying welding speed and five different shielding gas mixtures of argon and helium, has been defined with the view of producing crack-free autogenous welds. The bead appearance and the microstructure of the different welds were correlated to the welding parameters, whose main effects have been analysed. Welding defects such as humping occurred when using gas mixtures with relatively low content of helium, and when using relatively high welding speeds. Crack-free autogenous welds have been produced without preheating when using a high content of helium and relatively low welding speeds. Thus, this study has demonstrated that a helium-rich shielding gas is required for welding thick tungsten plates. Moreover, the low thermal shock induced by the process, coupled with the purity of the tungsten plates used, strongly contributed to avoid the occurrence of any crack.

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“…Most tantalum applications require the removal of Al, Fe, Cu, Mn, Cr, Ni, Nb, Na, Li, K, Ti, W, Mo, Si, U, and Th impurities to ppb/ppt levels for high electronic performance [6]. Recycling technologies for tantalum metal include hydrometallurgy, which involves the separation and purification of tantalum metal from tantalum scrap through chlorination [5]; reduction of Ta 2 O 3 by carbon calcium [7]; reduction of hydrogen by TaCl 5 [8]; molten salt electrolysis of K 2 TaF 7 or reduction by sodium [9,10]; and melting techniques using a high-energy heat source for purification, such as plasma arc melting (PAM), vacuum arc remelting (VAR), and electron beam melting (EBM) [4,11,12]. Pyrometallurgical techniques like alumino-thermic, magnesio-thermic, calcio-thermic, and sodium reduction have not been able to reduce the metallic impurities in tantalum below a few tens of ppm [13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, to achieve purities higher than 4N5, EBM was deemed appropriate as a high-energy heat source for melting and purifying, compared to other hydro-or pyro-metallurgical techniques. High-purity tantalum typically manufactured by high-energy heat source techniques such as EBM, VAR [11], and PAM [12]. EBM in a high-vacuum atmosphere (10 -4 torr).…”

Section: Introductionmentioning

confidence: 99%

Archives of Metallurgy and Materials

Yu¹,

Choi²,

Sim³

et al. 2019

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Electron beam melting(EBM) is a useful technique to obtain high-purity metal ingots. It is also used for melting refractory metals such as tantalum, which require melting techniques employing a high-energy heat source. Drawing is a method which is used to convert the ingot into a wire shape. The required thickness of the wire is achieved by drawing the ingot from a drawing die with a hole of similar size. This process is used to achieve high purity tantalum springs, which are an essential component of lithography lamp in semiconductor manufacturing process. Moreover, high-purity tantalum is used in other applications such as sputtering targets for semiconductors. Studies related to recycling of tantalum from these components have not been carried out until now. The recycling of tantalum is vital for environmental and economic reasons. In order to obtain high-purity tantalum ingot, in this study impurities contained in the scrap were removed by electron beam melting after pre-treatment using aqua regia. The purity of the ingot was then analyzed to be more than 4N5 (99.995%). Subsequently, drawing was performed using the rod melted by electron beam melting. Owing to continuous drawing, the diameter of the tantalum wire decreased to 0.5 mm from 9 mm. The hardness and oxygen concentration of the tantalum ingot were 149 Hv and less than 300 ppm, respectively, whereas the hardness of the tantalum wire was 232.12 Hv. In conclusion, 4N5 grade tantalum wire was successfully fabricated from tantalum scrap by EBM and drawing techniques. Furthermore, procedure to successfully recycle Tantalum from scraps was established.

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The arc-melting of niobium, tantalum, molybdenum and tungsten

Cited by 12 publications

References 16 publications

Preparation of 5N grade tantalum by electron beam melting

Preparation of 5N grade tantalum by electron beam melting

Effect of shielding gas composition and welding speed on autogenous welds of unalloyed tungsten plates

Archives of Metallurgy and Materials

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